Domestic boilers are used to generate hot water, which may be used to flow through a circuit to provide heating to a facility such as a home or office building. The hot water also may be stored in a hot water tank and used for hot water needs such as running a dishwasher, showers and other domestic hot water uses. Often domestic boilers are located in homes in non-living spaces. For example, they may be located in a utility closet, a basement, a garage, or in other parts of the home that is more associated with storage or utility than with a living space. When boilers are placed in storage or utility areas they are typically mounted on the floor.
Sometimes, for a variety of reasons such as limited storage or utility space, boilers may be located in living spaces within homes or apartments. In order to conserve space, the boiler may be mounted on a wall. There are several desirable features associated with a wall-mounted boiler, such as a small size and/or weight to facilitate the wall mounting. In addition, wall mounted boilers are often located in kitchens or other living spaces, and therefore it is desired that they have an attractive appearance. Most known domestic boilers are configured to be one or the other of a wall mounted boiler, or a floor mounted boiler. This provides a disadvantage in that it is not possible to use a single boiler type for the different applications of wall mounting versus floor mounting. Thus, there is a need for a boiler which is adaptable to a multi-position mounting whether it be wall or floor mounted.
As with any energy-consuming device, increased efficiency is always a goal. Some known boilers have reduced efficiency for a variety of reasons. For example, sometimes room air is used in the combustion chamber and burned and vented to the outside. This results in a loss of efficiency in that the room air which was used for combustion and then vented to the outside may have been first processed by a heating, ventilation, or air conditioning system. A more efficient use of energy would involve the use of bringing in unprocessed outside air for combustion and then venting the combusted outside air back to the outside, thus maintaining room air which has been conditioned within the home. Thus, it is desirable to provide a boiler that burns almost exclusively outside air rather than using room air for combustion.
Another factor which limits known boilers is that many heat exchangers used in boilers are cast iron. Many boilers limit the amount of cooling of the combustion gases because if the combusted gases are cooled too much, the water vapor present in the combustion gases (a byproduct of combustion) will condense and form a condensate which may corrode the cast iron heat exchanger. Thus, using a cast iron heat exchanger limits boiler efficiency because combustion gases must be limited in how much they can be cooled. Limiting the amount of heat harvested from combustion gases limits efficiency because heat is wasted when it is vented out with exhaust gases.
Another limitation of many boilers equipped with cast iron heat exchangers is that some of them use parallel flow configuration. This limitation is related to the restraint of the cooling of the exhaust gases as mentioned above. Parallel flow heat exchangers are a less efficient type of heat exchanger than a counter flow heat exchanger. Counter flow heat exchangers are often not used because they are so efficient that they cool exhaust gases to a temperature that is not acceptable. If counter flow designs are used in cast iron heat exchangers they may need to be controlled in order to maintain the exhaust gases within an exceptable range of temperature to a degree where they may loose efficiency and thus nearly lose the efficiency benefits of being a counter flow heat exchanger. Thus, there is a need for a boiler that is not limited to cooling exhaust gases to a temperature that maintain water vapor in vapor form.
Accordingly, it is desirable to provide a boiler which has an increased efficiency and is not limited to cooling exhaust gases to the temperature ranges that maintain water vapor in vapor form. It is also desirable to provide a boiler that is not limited to the use of parallel flow heat exchangers but can incorporate a counter flow heat exchanging design.
If a boiler is not limited in its cooling of exhaust gases, it will generate condensate as water vapor in the exhaust gases condenses. Accordingly, it is desirable to provide a boiler that can accommodate condensate forming in the boiler and/or can accommodate the corrosive effects of the condensate.
Efficiency may further be increased by pre-heating outside air before combusting it. Accordingly, it may also be desirable to preheat the outside air.
Another way in which efficiency may be lost in boilers is that the controller of the boiler is often in an on/off type control. When additional heating is required, the boiler turns on, when less heating is required the boiler turns off. This type of configuration of on/off control loses efficiency because turning the boiler on may create heating of hot water than is required. A boiler which may be controlled to increase and decrease output and be turned on and off is a more efficient design. In addition, a controller that monitors a variety of boiler conditions can make more accurate control manipulations to the boiler and thus increase its efficiency.
Accordingly, it is desirable to provide a boiler controller that monitors a variety of boiler conditions and controls the boiler to not just a on/off condition but rather on, off, increase or decrease boiler function.
Another desirable feature of nearly all manufactured goods, not just boilers, is to simplify the design. Simplified designs are more cost efficient in production and often require less maintenance than more complex designs. As previously mentioned, many known boilers use cast iron heat exchangers. These cast iron heat exchangers are often cast sections that are sealed and then bolted together. The multiple sections of the heat exchangers and the bolting together create complexity.
Accordingly, it is desirable to provide a heat exchanger without multiple sections, thus simplifying the heat exchanging design.
Simplifying a boiler design to permit more easy installation and maintenance of the boiler as also desirable. For example, location of the electrical connections in multiple places on the boiler complicates installation and maintenance of a boiler because service personnel have to hunt down electrical connections. Providing a boiler with easy connections to ducting and venting will also simplify boiler installation.
Accordingly, a boiler designed to simplify installation and maintenance is desired.